(a) Field of the Invention
The present invention relates to gas compressors, and more particularly to a rotary slant shaft type gas compressor having a multi-stepped exhaust system for selectively exhausting gas compressed in a cylinder according to a pressure of an exhaust channel.
(b) Description of the Related Art
A compressor is a machine for increasing a pressure and a potential speed of a medium by applying power from the outside. Such compressors are called fluid compressors since a fluid is an object of the compressor regardless of the state of the medium being compressed. As the media which may be compressed by the compressor, there are gasses such as air, nitrogen, oxygen and the like, and liquids such as oils or refrigerants. Even though a compressor to be described hereinafter may be used for compressing liquids such as oil, a gas compressor that compresses gasses such as air will be principally described.
As a publicly known gas compressor, there is a reciprocating compressor that compresses gas with a piston that carries out a simple reciprocation motion.
In general, the reciprocating compressor is formed with a cylinder, a piston reciprocating in the cylinder, and a cylinder head comprising an intake valve and an exhaust valve at an end of the cylinder, like an engine of a vehicle. In such a reciprocating compressor, intake, compression and exhaust of gasses are carried out while opening and closing the intake valve and the exhaust valve according to a gas pressure in the cylinder as the piston rectilinearly reciprocates in the cylinder.
This reciprocating compressor has, however, a disadvantage in that the intake valve and the exhaust valve mounted in the cylinder head directly contact the cylinder head or the piston during the gas compression stroke. The collision of the valves primarily induces mechanical noise, and bending or damage of the valves occurs in long-term use. Further, the reciprocating compressor has disadvantages in that a pulsation phenomenon is generated in the case of gas compression since the intake and the exhaust of gas occurs alternately in the cylinder, and that friction noise is generated by the instant expansion of the gas when opening or closing the valves.
An intake/exhaust muffler is provided to resolve the noise problem of the reciprocating compressor. However, if a muffler is mounted on the reciprocating compressor, the compressor itself becomes complicated mechanically and the number of required parts increases. Further, the gas resistance is increased due to the mounting of the muffler, thereby degrading performance of the compressor.
A slant shaft type compressor is disclosed as another gas compressor in Japanese Laying-open Publication No. 61-65081 (Apr. 3, 1986).
In the compressor disclosed in the publication No. 61-65081, rotation force of a rotation shaft is transmitted to a swivel plate, which is connected to pistons, for converting the rotation motion to a rectilinear reciprocation motion. In the compressor, a cylinder block formed with six cylinders is fixed to the rotation shaft and respective cylinders in the cylinder block are formed in a structure such that a surface facing a piston is open. The open cylinder is closed by a float valve formed with an intake/exhaust hole and a compressor case head contacts a rear surface of the float valve. A rubber ring is interposed between the float valve and the case head for preventing leakage of gas compressed in the respective cylinders.
In this compressor, if a driving shaft is rotated by rotation force transmitted from an external power supply, the cylinder block fixed to the driving shaft rotates together with the driving shaft, and the swivel plate connected to an end of the driving shaft rotates in response to the rotation of the driving shaft, so that the respective pistons rectilinearly reciprocate in the respective cylinders, in sequence.
According to the characteristics of this compressor, the respective cylinders rotate as being opened while the float valve and the case head do not move. The respective cylinders take in the gas through the intake hole of the float valve for gradually compressing the gas while rotating, and exhaust the compressed gas through the exhaust hole of the float valve toward a gas channel formed in the case head. In the above compression stroke, the float valve moves close to the cylinder block by a difference of gas pressures applied to a sectional area of the cylinder and a sectional area of the valve.
Comparing the compressor disclosed in the publication No. 61-65081 with the prior art reciprocating compressor, the piston of the compressor of 61-60851 reciprocates in parallel with the driving shaft direction, thereby allowing the manufacture of the compressor to be compact. Further, the compressor of 61-65081 does not employ reciprocating intake/exhaust valves but a fixed float valve, so that the mechanical noise caused by the direct collision between the valves and the cylinder head may be completely prevented. Furthermore, the compressor of 61-65081 exhibits compression efficiency and noise characteristics due to the gas pressure difference equal to the prior art reciprocating compressor in the case of continuous operation under a rated load.
In spite of the advantages described above, the compressor of 61-656081 has a serious disadvantage in that the cylinder block has to rub the float valve to maintain the seal between the rotating cylinder block and the stationary float valve, thereby causing abrasion of parts due to the continuous friction therebetween. In order to remove friction heat generated by the friction, the gas to be compressed has to be lubricative. Therefore, the gasses compressed in the compressor are limited to those having the lubrication property.
Further, the compressor has a disadvantage in that additional parts for emitting heat to the inside or the outside or absorbing the heat is needed, since the compression heat generated in the process of the compression of the gas in addition to the friction heat is very high. However, the compressor of 61-65081 does not suggest any heat removal parts, so durability of the compressor is degraded and gas compression efficiency is decreased by the various heat generated in actual use.
Considering the compressor of 61-65081 aerodynamically in view of the structure of the compressor, the compressor has a very big difference between a maximum pressure (Pm) in a compression section and an exhaust pressure (Pd) in an exhaust section. In this case, as the pressure difference between the two sections becomes larger, the aerodynamic noise generated when compression gas of a high pressure is discharged to a low pressure state becomes larger. Considering the compressor of 61-65081 with the prior art compressor on this issue, the compressor of 61-65081 exhibits a larger aerodynamic noise than the prior art reciprocating compressor due to such a big pressure difference.
Considering a compression load in the cylinder generated during operation, the compressor of 61-65081 exhibits a change width of the compression load per a unit time period much larger than that of the prior art reciprocating compressor. As the change of the compression load in the cylinder becomes larger, an axial force load applied to the driving shaft becomes larger. Therefore, in the compressor of 61-65081, the axial force load which is proportional to the compression load is applied to the swivel plate connected to the end of the driving shaft, directly influencing ball bearing parts mounted between a lower part of the swivel plate and the case, thereby degrading the durability of the compressor itself.
As described above, the compressor of 61-65081 has problems caused by the structure in spite of the various advantages over the prior art reciprocating compressor, so the compressor has a commercial limitation as a gas compressor.
Therefore, the demands for a new compressor of a structure that may maintain the basic characteristics of the slant shaft type gas compressor but resolves the disadvantages of the compressor of 61-65081 to minimize the aerodynamic noise, improve the durability of parts and accessories, increase the energy efficiency, minimize the number of required parts, and achieve loadless operation are increased together with demands for diversifying of the gasses to compress.
The present invention is derived to resolve the above problems of the prior art, and it has an object to provide a rotary slant shaft type gas compressor for discharging gas compressed in cylinder bores, not at once, but selectively in association with an external pressure.
It is another object of the present invention to provide a rotary slant shaft type gas compressor with a structure that may be designed aerodynamically for minimizing the noise mechanically and aerodynamically.
It is a further object of the present invention to provide a rotary slant shaft type gas compressor in which power required for compressing gas may be minimized to maximize the energy efficiency.
It is a still another object of the present invention to provide a rotary slant shaft type gas compressor in which a change of a compression load per unit time period may be minimized for improving the durability.
It is a still further object of the present invention to provide a rotary slant shaft type gas compressor in which gas to be taken into respective cylinder bores is first circulated through a crank chamber and then introduced into the cylinder bores.
It is a still another object of the present invention to provide a rotary slant shaft type gas compressor capable of operating loadlessly with a high efficiency.
It is a still another object of the present invention to provide a rotary slant shaft type gas compressor in which friction heat generated inside and compression heat generated by air compression may be effectively emitted.
In order to achieve the above objects of the present invention, a rotary slant shaft type gas compressor includes a valve plate contacting a rotating cylinder head and formed with an intake groove and a plurality of exhaust grooves, wherein the valve plate is fixed to a case head for selectively discharging gas compressed in cylinder bores.
In more detail, the rotary slant shaft type gas compressor includes: a driving shaft integrally formed with a cylinder head perpendicular to a driving shaft axis, the cylinder head being formed with a plurality of gas holes on a concentric circle at uniform intervals; a gas guide member formed with an intake manifold for intake of gas from the outside and an exhaust manifold for discharging gas compressed in cylinder bores to the outside; a case head member for rotatably supporting the driving shaft formed with at least one intake port for supplying the gas taken in through the intake manifold to the inside of the cylinder bores, and two or more exhaust ports for discharging the gas compressed in the cylinder bores to the exhaust manifold; a valve plate member fixed on an inner surface of the case head member to contact an outer surface of the cylinder head, and formed with a gas intake valve groove and at least two gas exhaust valve grooves on a periphery on which the gas holes move, the gas intake valve groove supplying the gas taken in through the intake port to the inside of the cylinder bores and the gas exhaust valve grooves discharging the gas compressed in the cylinder bores to the exhaust ports; a cylinder block formed with a plurality of cylinder bores in parallel with the driving shaft and having a surface integrally coupled with the cylinder head, and having an opposite surface slidably inserted with pistons in respective cylinder bores for compressing the intake gas in the respective cylinder bores; a swivel plate member connected to a center part of the cylinder block with a coupling, and connected to the plurality of pistons via piston rods, for converting the rotation force transmitted from the driving shaft to rectilinear reciprocation motion to be transmitted to the pistons; a case end plate formed with a slant surface for supporting the swivel plate member; and a case coupled with the case head member and the case end plate for incorporating the cylinder block and the swivel plate member.
In the rotary slant shaft type gas compressor of the present invention, the respective exhaust ports of the case head member incorporate respective check valves for selectively discharging the compressed gas via the respective exhaust grooves of the valve plate member according to an internal pressure of a compression tank.
The case head member and the driving shaft are formed with a circulation circuit for introducing the gas introduced from the intake manifold to the cylinder bores via a sealed crank chamber formed inside the case, so that aerodynamic noise possibly generated when compressed air remaining in the cylinder bores after an exhaust stroke is finished is met to new intake gas may be limited in the case, thereby minimizing the noise.
Further, a tension ring and a ring-shaped plate spring are inserted between an inner surface of the case head member and the valve plate member, so that the gap possibly generated by the friction between the valve plate and the cylinder head for a long term use may be completely prevented.
The rotating cylinder block and the swivel plate member are connected by a universal coupling or a spring coupling, so that the mechanical noise generated while the operation of the compressor may be minimized.